Chain saw bar



M. MERZ CHAIN SAW BAR Jan. 31', 1967 Filed May 8, 1964 United StatesPatent Ofifice 3,301,283 Patented Jan. 31, 1967 3,301,283 CHAIN SAW BARMax Merz, Los Angeles, Calif., assignor, by mesne assignments toNicholson File Company, East Providence, R.I., a corporation of RhodeIsland Filed May 8, 1964, Ser. No. 365339 4 Claims. (Cl. 143-32) Thisinvention relates to an improved chain saw bar and more particularly, toa chain saw bar having an improved chain supporting structure.

In the past it has been the common practice in the chain saw art toprovide chain saw bars with a removable chain supporting wear stripswithin the groove of the bar. However, the typical type of removablewear strip used for this purpose is usually preshaped in some multiplaneor multicurved relation to complementally engage a similarly shapedbottom in the chain saw bar groove to support the chain passingthereover. The multiplane and multicurved wear strip and complementalchain saw bar supporting surface therefor are relatively expensive andcomplicated to manufacture, use and maintain due to the complicatedconfiguration thereof. Also, by virtue of the preshaped configuration ofthe wear strip, only one side surface of the strip is capable ofsupporting the moving chain and therefore must be discarded when thatone surface becomes worn.

It is therefore highly desirable to provide a chain saw bar having aremovable wear strip which is improved so that the wear strip need notbe extensively preshaped in various multiplane or multicurvedconfigurations and instead is normally a straight piece. Likewise, it ishighly desirable to provide a chain saw bar within the wear stripsupporting surface in the bottom of the bar groove is a single bowedarcuate surface terminating in dovetail anchoring means which is used inconjunction with the straight wear strip to provide an economical andrelatively simple structure having a space between the wear strip andthe bowed surface to anchor the wear strip and yet allow it to flex alimited amount in its support of the saw chain. It is further highlydesirable to provide a relatively simple straight wear strip which isadapted with two alternative chain supporting surfaces which may beselectively utilized to provide more wear surface than conventional wearstrips and which will naturally correspondingly provide longer wearstrip life.

It is the primary object of this invention to provide a chain saw barhaving an improved wear strip chain supporting structure which isrelatively more simple and economical to manufacture, use and maintainthan are the presently known types of wear strip chain supportingstructures.

A more particular object of this invention is to provide an improvedchain saw bar wear strip supporting structure wherein the wear stripsupporting surface is a generally bowed single arcuate surface.

Another more particular object of this invention is to provide animproved chain saw bar wear strip supporting structure wherein the wearstrips are resilient and formed in a normally straight configuration sothat the wear strips are maintained in a bowed configuration on thebowed bar supporting surface when the ends of the strips are anchoredagainst movement.

Another more particular object of this invention is to provide animproved chain saw bar wear strip supporting structure wherein improvedwear strips having normally straight resilient configurations arepositioned in substantially spaced apart bowed relation with the bowedwear strip supporting surface of the bar with only the end portions ofthe wear strips in normal engagement with the supporting surface.

Another particular object of this invention is to provide an improvedchain saw bar wear strip supporting structure wherein the wear stripsare symmetrically constructed with dihedral end surfaces for alternateselective engagement with dovetail anchoring means adjacent the ends ofthe bowed supporting surfaces whereby the wear strips may be placed inmore than one selective supporting engagement position with respect tothe chain to be supported thereby.

A further more particular object of this invention is to provide animproved chain saw bar wear strip supporting structure wherein the wearstrips are symmetrical and are provided with symmetrically tapered endsurfaces so that the wear strips may be selectively placed in any one ofseveral selective positions to provide more than one wear stripsupporting surface for engagement with the chain.

Another more particular object of this invention is to provide animproved chain saw bar wear strip supporting structure wherein the wearstrips may be cylindrical or rod-like and may be provided with conicalend portions in engagement with complemental means on the bar so thatthe various portions of the cylindrical surface of the wear strip areavailable for supporting engagement with the saw chain moving in thegroove.

Other objects, advantages and novel aspects of the invention will becomeapparent upon consideration of the following detailed description, inconjunction with the accompanying drawings wherein:

FIG. 1 is a side view of a chain saw bar showing the relative positionof the part thereof including the novel wear strip chain supportingstructure.

FIG. 2 is a partial side view of the bar showing the anchoring chainsupporting wear strip structures pertinent to the subject invention.

FIG. 3 is a partial isometric view of the end of one end of the wearstrip showing the basic shape thereof.

Referring to the drawings, there is illustrated a chain saw bargenerally designated by the numeral 10 which is adapted at the left(FIG. 1) to be secured to the chain saw drive assembly (not shown). Thechain saw bar 10, includes generally, a center spacer member 11, outerguide plates 12, a saw chain 13, a typical chain supporting bearingassembly 14 and wear strips 15.

The guide plates 12 are respectively secured to the sides of the spacer11 by rivets, bolts or similar securing means 16 and are larger than thespacer 11 so that a groove 20 is formed adjacent a periphery of thespacer 11 and between the plates 12. A bearing assembly 14 is securedbetween the right or outer end portions of the guide plates 12 (FIG. 1in a bearing retainer aperture 23 formed in the plates .12. The bearingassembly 14 is adapted to receive the chain 13 to guide the chain aroundthe outer or end of the bar 10. The spacer 11 is provided with generallybowed arcuate surfaces 24 over which the wear strips 15 are to bepositioned in bowed arched relation thereto for slidably supporting thesaw chain 13 in the groove 20. A r i The wear strips 15 are made ofresilient material and normally substantially straight in form (lowerstrip 15 FIG. 1). The wear strips 15 are provided with opposed lateralwear surfaces 21 and dihedral end surfaces 22 intersecting at an angleB. The strips 15 are bowed and anchored to the bar Within the groove 20by anchor retaining structures 25. The structures 25 extend into thegroove 20 and are provided with a retaining surface 26 which intersectsthe bowed surface 24 of the spacer 11 at a dovetail angle A which issubstantially equal to the angle B. The inventor has found throughexperimentation with working examples of the invention that the mostreliable results were obtained when'the angles A and B were in atwenty-five to thirty-five degree range.

Thus it can be seen that the surfaces 26 of the retainers 25 form adovetail retaining groove at the bottom of groove 20 and may be sospaced apart that when the wear strip 15 is bowed and insertedtherebetween the wear strip will normally rest in a bowed spaced apartrelation with respect to the bowed surface 24 of the spacer 11 and willengage the surface 24 only adjacent the end portions of the wear strips15 (FIGS. 1 and 2). In this position, the outer dihedral surface 22(away from the surface 24 of the space-r 11) will engage thesubstantially complemental surface 26 of the respective retainers andpresent an outer wear surface 21 for resiliently and slidably engagingthe chain 13 in the groove 20.

The wear strip may be removed from the bar by enlarging the bowedthereof so as to shorten the bowed length thereof and by removing oneend of the wear strip from engagement with the respective retainer 25.The strip 15 may then be rotated 180 and returned to the bar in ananchored supporting position as previously pointed out with the otherchain supporting surface 21 in supporting engagement with the chain 13.Thus the chain supporting wear strip structure of this inventionprovides, among other things, more than one wear surface on each wearstrip and thereby provides double wear strip life.

Further, it should be noted that the wear strips of the chain supportingwear strip structure of this invention are easily inserted and removedby bowing the wear strips. Also, the resilient wear strips 15, when inchain supporting position, are capable of flexing relative to the spacer11 by virtue of the spaced apart bowed and arched relation therebetween.Further, it should be noted that the spacer 11 is provided with arelative simple wear strip supporting surface, namely, the singlegenerally bowed surface 24 and does not require particular multicurvedor multisurface wear strip supporting surfaces.

In addition, a cylindrical wear strip with conical or dihedral taperedends could be utilized in this invention.

It is to be understood that the invention is not to be limited to thespecific constructions and arrangements shown and described, except onlyinsofar as the claims may be so limited, as it will be understood tothose skilled in the art that changes may be made without departing fromthe principles of the invention.

What is claimed is:

1. A- chain saw bar comprising a center spacer member having aperipheral wear strip supporting surface, side plates secured to saidspacer member and extending beyond the peripheral surface of said spacerto form a groove for receiving a chain saw chain, retaining meanssecured to said spacer member adjacent the ends of said peripheralsurface and having retaining surfaces respectively forming dovetailangles with said peripheral surface, and a resilient normally straight,elongated symmetrical wear strip having tapercd dihedral ends, each ofsaid ends having opposite inclined surfaces arranged symmetrically aboutthe longitudinal center line of the wear strip adapted to respectivelycomplementally engage said retaining surfaces to hold said wear strip inbowed arched relation with respect to said supporting surface forresiliently and slidably supporting the chain saw chain in the groove. il

2. A chain saw bar comprising a center spacer member having acontinuously arcuate peripheralsurface, side plates secured to saidspacer member and extending beyond the peripheral surface of said spacerto form a groove for receiving a chain saw chain, retaining means formedon said bar adjacent the ends of said arcuate surface and havingretaining surfaces forming an acute angle with said arcuate surface, anda resilient normally straight, elongated and symmetrical wear striphaving dihedral ends, each of said ends having opposite inclinedsurfaces arranged symmetrically about the longitudinal center line ofthe wear strip adapted to alternately complementally engage saidretaining surfaces to hold said Wear strip in bowed arched relation withrespect to said arcuate surface with the central portion of said wearstrip spaced apart from said arcuate surface for resiliently and.

slidably supporting the chain saw chain in the groove.

3. A chain saw bar comprising a center spacer member having acontinuously bowed arcuate peripheral sur face, side plates secured tosaid spacer member and extending beyond the peripheral surface of saidspacer to form a groove for receiving a chain saw chain, retaining meanssecured to said bar adjacent the end of said arcuate surface and havingretaining surfaces forming an acute.

angle with said arcuate surface, and a normally straight, elongatedsymmetrical resilient wear strip having dihedral ends, each of said endshaving opposite inclined surfaces arranged symmetrically about thelongitudinal center line of the wear strip adapted to alternatelycomplementally engage said retaining surfaces to hold said wear strip inbowed arched relation with respect to said bowed surface for resilientlyand slidably supporting the chain saw chain in the groove.

4. A chain saw bar comprising a center spacer member having acontinuously bowed arcuate peripheral surface, side plates secured tosaid spacer member and extending beyond the peripheral surface of saidspacer to form a groove for receiving a chain saw chain, retaining meansformed on said bar adjacent the end of said arcuate surface and havingretaining surfaces forming an acute angle with said arcuate surface, anda resilient normally straight, elongated and symmetrical wear striphaving dihedral ends, each of said ends having opposite inclinedsurfaces arranged symmetrically about the longitudinal center line ofthe wear strip adapted to alternately complementally engage saidretaining surfaces to hold said wear strip in bowed arched relation withrespect to said arcuate surface for resiliently and slidably supportingthe chain saw chain in the groove.

References Cited by the Examiner UNITED STATES PATENTS 2,888,964 6/1959Mall 143-3210 2,897,856 8/1959 Carlton 14332.10 3,191,646 6/1965 Merz14332.10

FOREIGN PATENTS 578,826 7/ 1946 Great Britain. 930,538 7/1963 GreatBritain.

DONAL]? R. SCHRAN, Primary Exarrn'r er

1. A CHAIN SAW BAR COMPRISING A CENTER SPACER MEMBER HAVING A PERIPHERALWEAR STRIP SUPPORTING SURFACE, SIDE PLATES SECURED TO SAID SPACER MEMBERAND EXTENDING BEYOND THE PERIPHERAL SURFACE OF SAID SPACER TO FORM AGROOVE FOR RECEIVING A CHAIN SAW CHAIN, RETAINING MEANS SECURED TO SAIDSPACER MEMBER ADJACENT THE ENDS OF SAID PERIPHERAL SURFACE AND HAVINGRETAINING SURFACES RESPECTIVELY FORMING DOVETAIL ANGLES WITH SAIDPERIPHERAL SURFACE, AND A RESILIENT NORMALLY STRAIGHT, ELONGATEDSYMMETRICAL WEAR STRIP HAVING TAPERED DIHEDRAL ENDS, EACH OF SAID ENDSHAVING OPPOSITE INCLINED SURFACES ARRANGED SYMMETRICALLY ABOUT THELONGITUDINAL CENTER LINE OF THE WEAR STRIP ADAPTED TO RESPECTIVELYCOMPLEMENTALLY ENGAGE SAID RETAINING SURFACES TO HOLD SAID WEAR STRIP INBOWED ARCHED RELATION WITH RESPECT TO SAID SUPPORTING SURFACE FORRESILIENTLY AND SLIDABLY SUPPORTING THE CHAIN SAW CHAIN IN THE GROOVE.